SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79831b6bfc5315f27e3d8e75a349ae6403861f6b77227fb594358e718f00c0c1' 
  AND token = 'Skv9BJw9Swo8zWQq8DnoC9JEtJgZgHXGfm5zYf8hWK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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