SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15e498a25b3877507fd6d16ef60d425301fe683281da7558203d4edead130485' 
  AND token = 'pQT7fB+8kwKv/n8alW/ZFzvrdMJVAkKwiFtBQZdYY40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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