SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a35911f97d73e0a4026a5e17dbdda20303015511a4a636fa0878859413e2a14a' 
  AND token = '7yX94UbKjSrGutxo//j9/KHd1bEAesXfHFL6J1afb/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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