SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '996643ba947176755cf52dac821e442a91fb6b61cbe151ab86b4573861e39a1f' 
  AND token = 'X4ZGZx6NcUe4fqj5VNkuzCQKqGLyjgCgjhdKTt/duB0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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