SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '275e2554b7544a995703fc28dee27c8fe8b943d1560d101e4228f62d88fd289f' 
  AND token = 'JqBt8EpJt0BB2wTC/3lJV9HlnlnwNDdv+JMxKddtQBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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