SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '62b4f7b2dc1e3868bfb40cd6f867d300739d2adafa9c93e875405f2dcaffc4eb' 
  AND token = '2+MbkrJM6HLYTEMZzI3W/Xv2d8h9WFfl5F9qR5xzfaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00007

JSON explain

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