SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bb0837335371808f911128920b6a4ef039045c07be7a0e7c054dbbf8b2235abb' 
  AND token = '579PTEmgo0Y1juHzyRVyivZDvkHfRBjKr2cTrh3iJcw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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