SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '2b5ac3cc0e8cba641ad912fda8d9a1fcb94b11a8266b433adf440c9c3557cbcb' 
  AND token = 'q8Uwh1HFrb9YEUcJEfYKj50HcgRALY7eefU7k4936uk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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