SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a247d2de27d5da7493731ed62a56bcedc16b79d5910ae123a8fef04eafcea871' 
  AND token = 'fDRv0Qg9rv5hnXW4O5aixNW5yBC9+boJI7WVw5rTxDw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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