SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6075e73c795d2c633627db133e943aa12f68248b9576c9a23127402d85af3a33' 
  AND token = 'txKZi3EJB/6+K5TGmxR8YIrDG1HguqAQVqZw/nrfhjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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