SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac9d81c273d9697655faf8934af61fe84d744f90d044b0dbb4743eb838b439b6' 
  AND token = 'cJo/DoHwg/OdkM/mZrBBQB1+7GZAomsjrhDWzTg5MfM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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