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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e0ee2c96c97160b9d3053643e9def3dc34439f79b368794e51e4cab31cef3f6' 
  AND token = '+nYcF4feU2n+KNHL6OaVZ9ezwC/t5KaCwOz4KfOoAvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}