SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14dba89ffa235c5f40990a028d1d6a9c6a539ffa9469a57a58344bd66c7ee4d8' 
  AND token = '8mtLncKbE52PEGRnTP6jQa7gS2AD25gJWBaOXbA5GDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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