SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b49239b266bd11058a4364c9a04770699854b089a718f718c603084872135e96' 
  AND token = 'W8XGmp6lezCQWA11fDzkIvhvT49gl4gfm1GDZ5UJjDA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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