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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3a191d3bcbbe52e88761911a12f71a2612861deff28f57f15229e9445ee5e69' 
  AND token = 'WfRA1A/PZE3cF9uv2UFoPvcSGRHgrl4eIUK64uxY4KI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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