SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7b63e762200f6ce45fee6a5b89d33490556ef12588c4c6d9d2099fa08e1912b' 
  AND token = 'LTrzBlSz6XeYHqq6jJULjav+hf24gcuyzSgeBknFemk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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