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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '173c318c3466ce27864047ea6e6ff09805a4c7f77ff3a5d6ef88299544f4936c' 
  AND token = '3+tQMMUs/Nm8boWCzpEqTUBGbIaIks4HFTAXTQT0Yxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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