SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c784b9f32737e5d70c734c585dcc9747ea3628c045491f7aee67132a23c849f8' 
  AND token = 'oTsOhhEehw6XsoenigAaiHrQchnM4SmbYx4TpZDpo6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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