SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de77b7737aa64a57a98dd71641f9fa53e9ec0e0fa092520db437b8ad0c0bb710' 
  AND token = 'BJuKFtxMAlpDziFyeCgNX3+jAyQ8jZztVvsJ6ZiTkJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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