SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef047028c39bf3ef74715838fcae7d218fe9acfb7a4409507b7ec041b49aa6f0' 
  AND token = 'F/SDWQf5WrBI6vHqCeJa2P0zmH2s1bm4bzk0+UGYnsk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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