SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55aaee9195e174f98d93047d5fdeb5e9a67f1ffbbfab00d59ccc52c847ce71f9' 
  AND token = 'mzxQQX5iWwn548cy6JUqbOntVTqbzImYlxNGd9z6+qk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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