SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16d0f3e816a5fbd99e47c6f7294ebd0a0deba899654516fd37003d158b0facbf' 
  AND token = '0ClfoYCKSHcvsS2Bm9cabOkbzzD1WUYUXd2Ic5DrASQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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