SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e38c7dd499693da4e82d34dfddbeed870524bbaead4faa2df679ef31c0813330' 
  AND token = 'vwDlleCa0qAifov2mW2kiK+lnVCoB9cOgM0+oy8EASg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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