SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f6505a8d4cf7952530fa889014a8c2310f229badb2cc49e9d6de88d66f43f16e' 
  AND token = 'K4mgmn9y+/PpgHn/SxVLJuzUPWP6bEzzceDSquyGgNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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