SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a249d33cc2201487cd776b12d4bf44c4d3ef7d59f2de4e2fdac7978ce92cf731' 
  AND token = 'xHGt+yGLIOAlAEhhsRksMaVWxWXbY+3570l8CICNCWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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