SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4a8a706db8c764618b1f77ba15f10f575d332c9e4dca8c59dfe67f2d09a4b94c' 
  AND token = '/AUQjfe5wkasmyBh8IGBLcZs2+PrUSz1dPwCpNP6yQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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