SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c8effb9f2aa8f3d4c914cb975a58325c704ca1cde2bc965dafcaf25308b3947' 
  AND token = 'AMgEmZSwrGvqR7+z+ZrgeXvJ+8/MGqm0RYjLwSkQ2Bg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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