SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14d6b7f95360983d89b6290269ba8a858706ff84b89060f4e94ec1bb00b9f856' 
  AND token = '7vPjxFT/PP5vYbb8lTnyKI7dB/QWmy2ZdL/SqZJgCsk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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