SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7ec348580a3b252c52281da535b0f004006e304428878826e11f615acf3c58a' 
  AND token = '1FEQuVexbmJhYSiDbX7Dnd7o8FsPi9eHQeTfJNnXZGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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