SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cf1fa65c5ad248483ca46854dab3fff1642a90c8c46fe90efbd2d550b2ed8e99' 
  AND token = '7ySS4D3fisEHUFUHjqBYugS711xUCXSIml8ichaqMFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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