SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8a13fa828c5808c144936f167904c335e18c8a7ce57784e050bfa390add3e2f' 
  AND token = 'w+HxMz0piGvLYAWYsTJKgBAMdp5IwGZelfjK8C1cNrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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