SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '504809e810ee059346b2cef1d3a51d5500dd3e30e33b741c15cf7767fff42b5a' 
  AND token = 'BqtTKzN4j6nZAJG4bOpJbjbn0aRqPOW+bsL5j3PD/W8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

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