SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8df752e8ecda5079417a0ebe06653f263d24577fc3ae734927142941137be993' 
  AND token = '2h6pZLwcZNNxrPcEa1h0x35id0++X91HTnBXHtT0bt0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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