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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '174dc8a7d02a6c6bc9766f9be2260c9dc89a42ec7b1438d1c48bbfca6e53e1a3' 
  AND token = 'UJS2CTbbP3vWxNM5xzpAZj0Ua+zG7Wrjzz4Df9CL038=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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