SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a82de81b4f749bcf5f4d5e02883465672a311a88b78a49f988361a06b0d55887' 
  AND token = 'vTKMOHJ4bu6fApv+fGzObMBvkFO7ZAzk2pVBzShlRA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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