SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f77d6a544cf1b64d1c1a84558a9a9661bb08e551fbe5731944153ce6319780ac' 
  AND token = 'FFUWVYg4FNCahyawIUO2zeu6SONsUfn9VsG876qfRto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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