SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'db1c87104d8f689069e4d4d986969a5ea4b363e924154c26f1b0c0720bd47cb8' 
  AND token = 'BqqXvYHHg9/ues2JmnrdSlAvctNzrijBSkEL/Vi8wBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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