SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '246211de528a5e007f6da1a8c5284f4f859486a3b7c0f4a37950c98c7706c912' 
  AND token = 'xUK5OQpwejTnSzehDQTfQkueVWUARq8wya+QBL1omQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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