SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd52f40f535921f89cc4aa9509cfc86a721ba38beefafdc6baa970c8f1c184f65' 
  AND token = 'YBdSHsjQwugQxv7GyI9acfr2Zx+HeAbNCmKVJaYxKXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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