SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a3d669a4182774497c36a492f951841fa1932f210c024a8d0963f449671afdc' 
  AND token = 'FGn+BSqevLcsCj9cRvg1vg+V/Nj3q/jXeFXrtnFczSw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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