SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da9c1172e524fc70aa5b6a101ccd35a23f46d44bc6d660611fd5d65fef5200a6' 
  AND token = 'eWGHmVqIiLXPbl2fydIUEx8gUi99Wu0LnAUDOsbI+Kk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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