SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28fd17cac648439b40128238207a6c9aad15b07e80e48b802d0ad6aff5cc4af4' 
  AND token = 'zy0VewsuP301crSPxa7p6wUKSKB2s+nsiVB/qgjbDhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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