SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52147cd87eae2ba50938be70c32672e4ca971f473298e41b6b543930cb19b19c' 
  AND token = 'UZneYdqMWusPzjhVCJiwkgx+2DKKo89p+7BUvLxTRaY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}