SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '770d30fe4c0dd2b35c5b89d56a0f242a9d58803b104f7451fd896d1d7ebde9db' 
  AND token = 't3Ywxu9gHZlrV2ZsbFJdQ5cvIGdVYqAlOKCvLNhV0dA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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