SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bfc7163d9546a5e3b46f2c6782080da811fed5e84d6d05071a22a92191faeaa' 
  AND token = '4+QjuwfMQTVr82nv20hH9gFvUlv43uFyMzUNE80nbw8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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