SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e714ee3db0e47429d347d6f9867c4346c80869bb81470fce17d71f8a17ba8e9c' 
  AND token = '5UPUEeZqoO2eQsjbAif0pxIorrO4It6eJwfMfJ+EpWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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