SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '755a154985156df159d374c39bf3bf8ad3a595e310270c180d0bfa7b84b20350' 
  AND token = 'lAZgSbc8fvmweQ1qUYmOZdMFX8oj4x9G89GabzlN+T8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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