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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9a6ea29431141998a91c323680b7cad8caf53b00f51f4e4e8f928c3c49147ac' 
  AND token = 'UukQLnQtZ0bQGAzv0YpcKQ9c7Wl9wNbqGWHEVM5NkgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}