SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17c5f47e687f1dec015712b5c9f8e2a7656eda1eba3c91548b546f9512e9f500' 
  AND token = 'wUkIjWwpBhBbcUSS/kzIJb3j4jLgxJerPOG20MtjI7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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