SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27c358f7a387899561cddfa2fcb473da93e22c5a41f545bfce9b84a736edd2ad' 
  AND token = 'pSvl0hgqUn79sA8LIEfoawlRF6jCw90JcDiQMNPYQOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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