SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6e6283fac7743fc13fd0da822e1f3911fcc9ddf3476f27f64f61ef103738172' 
  AND token = 'BpoGhLr4PccM4ao+wdKGZ7ummaH3jFWMeyHd3AkOLAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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