SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f50d27ac9de1d36b78515d0a1ff5e4d8cc95eb39fba16aa92174f153372a53bd' 
  AND token = 'D/M5sGLLCOau6GYg+lutQ0k4Vs9QsNIKJWPUA9FviNc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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