SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '313f7dd49fb6258eabfa11c6b79039a39d067c397ed7efd3a86d8523e02c71ae' 
  AND token = 'yKRo081BjL9i9srRhv/COqNksLAYsxnyBMwx82cZpKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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