SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dfc24fb9f54b13a3d45894b999cbb34e675d892065586f59df78ea63ef62393' 
  AND token = 'uOa1p+wZKE0kYr+7YgLHqa3NPqG6iRYsQKa8pOtUqgw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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