SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e335b89c46b7bd3dad2b6efda4715cd87287f0573541be61777fbd95e9696f5' 
  AND token = 'SYv/Qqr7yJLsoenCgy79jTrcVKclLfl5T/9ZtDd4hsk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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