SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1529a949f0d0312411a2bfdf2f1fd5018e88c6e846f634014c425ad9cb6352a' 
  AND token = 'F5mcL5k5HTQOhP6MJiSiYNbC5du3AkhirM+zlWpiiJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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