SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d6345e329dfbc84821f759da630a91b1480f7b6a0da8aad1f68b150a5bf9815' 
  AND token = 'DqswQe3vhKXzcl9rNJUrs5bLWXM0mdGABDPPN6nLwzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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