SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40350d5d96dc4a8740999e4848f46aa4e2f14312e9f7c2a3bc1696f0a766c958' 
  AND token = 'eEVUGLxbj/ccI9W4zUBVfSCV+jphefHQEfhfVKgjNqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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