SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0856e2269e068cd5657678d84359f9f03ed01782fb4fd5ebaa61bae1c942178' 
  AND token = 'G55lkFn994psXgjAWnqkpNTKEBZEIIO+mEck0kwwygY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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