SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e237f91b16feb99e1622f90b1eaa60caf4cb847f47ccc647c9f247b68ddef685' 
  AND token = 'KXKhlSve/nSzVgPw2vBtZOW8MqgQ98AFmmTdn5PRfqo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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