SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '703ffd69d16ac631670e1b93853a52b12ba9d1098cfa67593f57e77af9e8ed1b' 
  AND token = '0jt1IOT6Ek0ZMgUM6KRATzuTpZfLocTJakxnePM/jS0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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