SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3c108650a0fb8d279bba34b094684cded43f9c76992e7b7810d7e2ebcd39e71' 
  AND token = 'K0OLVe4IUuDyJC7t8jVQBfIWUkdlfM+7twEGTtXwR4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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