SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b88f1e030827e7e2cde9a9f40de901aba19035688bdd9415b0c75f014da3624b' 
  AND token = 'oEtaa0dQI0Q+1PCjywyoJNLng96TcozMhHHaoPZzS2o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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