SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f98feb8f1da4cdd5b8d9af166c40cb6c792ca143edc3fc1cb86c5b15b7aa280' 
  AND token = 'SVi/MhmWAnhluNFH5Jhz+rQ+sEyS9bUh+ezZ/iqB4/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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