SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8968731edd8cad7e43ba9ab447ef2ab71e1ef4e2ca52da402a05e20fef5303d' 
  AND token = 'Ew/nttIVcl0CewzcPzzcxSqqP9RifNYiJ7JhFBLL8xU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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