SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '52b19d5aed2c89af75ae73fc0c39ccb2c861c06baf34f5c2434281b444b47668' 
  AND token = 'MplzYiTZlApz3xntJRMT9FdWQUYN4DBD2eOf5WTyPZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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