SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5666f77e0bfe7b4b0eb000d8af04a626cad23c605bb278642c493b7eb1745de3' 
  AND token = 'q+cKDKUTllM3Pa49ZXGgVCow2jjjkvFycKhv4HhHW0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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