SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '993c5b051f1deccf7cc89cac336b6984b1d7a070238796238fa7b6bba25fd0e7' 
  AND token = 'U/5dT+IH3bDYgY8Kv4kjHXVdRPRH1rv8EnOmzhGPKik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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