SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1556b0d983e1fb475f11299a893a9b6f9ac540e3f2796abc90c628b8f1756ccb' 
  AND token = '5vPDOmLn4Hpbld3tikmL837Ysn3Chwwkx2TQqTiGWjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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