SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '647394470d409e4a860d99660be15e2f0257064b0d222ca9e583ef691924dd8f' 
  AND token = 'FHTf6QubvnsYlDM5v9v2Vv0BF1fUuKggAKyi+HZLIxw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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