SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c49e56362819a5738fbb91211d0b3e203199397fd07f1b7b42e6da58e694f333' 
  AND token = '0396A0oFOaeiK75UchCdPYIJ0JvTP8ZK8Q5uN6rzkY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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