SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98f2ef05804f10449e6d4475367c12405b1284245547dba04e9da72616030e48' 
  AND token = '8LskpSz/MA/qOJCPhNlOrV8PfCjsRmTZWMK1q9Z9GXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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