SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27ecbf9d11d17f6dd590c99600fe5a9d09bb1db4165f19c5931865b97594be28' 
  AND token = 'ncqL9Lpz57dsnxEPfvibvdpBZzjSFC68RKeqaCW8FBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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