SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f3a4118abf63f516ccb357636ac8e3b86a76a439bfef79c0997a8c95735bc99' 
  AND token = '31bATZJjr1faYl6o4YL62GomwcxDU6bsovCmF3xJB28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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