SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4fa324167b581123c9ebfbe34e99c0bc69e890e643fefe7940157381465a884' 
  AND token = 'DDAxQf0qzSV8uCjBK9wzXiHcEyK9LF3QlStj4iAOGwk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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