SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21a486aba826c051c87a448029810e959e00801c0f082a2333f02ccb9275e478' 
  AND token = 'womtYiP6wUcW0bcPU6vWa2NrGW2zmBWy3kLK05tJj3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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