SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c2545185d34c5d94417887303ec61ed9af419368a5a793029cc164e220f26701' 
  AND token = 'sOGOjadcn6JSEqOrX+W6mDgJhhlKeoqLvs8vCa1E+gQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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