SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dee5f2f71dfd8c6aa6e07eb7cc170ed478dcaf5ffebaa16783895a84ae2a476' 
  AND token = 'vDxo7KDQUwdJ358uvcn2b6fJjomjd9qHlxfbfhkHHtM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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