SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5a47f7030ac2063c350efb6e66a74e93228561acd7cefd50dce1b3ef939eef8' 
  AND token = 'VHVychoXq0ssaCfImxPxqKx0ZQY2f69CXqWMDCKYm+A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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