SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8817921642e7d07f35796e3be0bb437f7478afc8b9d4ce386084f7ca43dcb35' 
  AND token = 'ubPkEOKroHATvog2QodKJa54UeikQTwW2zXLcnexvY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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