SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8682ae90d1e84cffed2b8a08660303b0c9398f16ee914b511d3c06dadf245384' 
  AND token = 'gCWrZWTzFtPwAJK9OunLl5Fzx2taKMjXaEj3AQYN05o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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