SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f738ab4d5bedf20ee0cfb52188c9e462807313ed2b7e1b5301be29e6c6b2b4b8' 
  AND token = '/3gKZqlCi40ZYwk6VDkBtRENywxWHkDlCAmjF/IhxKQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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