SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9348979885478aa1537928ca72604441ce7286d656b76473fe5149deabd8923a' 
  AND token = 'vK39B9vyUas/VocXa+7PD0U4YMDTOkMQNflZzt9CKxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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