SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8a07e767509683e48ad136769e18e26ccc27e67be9691a4c1d4a017d02ac42f' 
  AND token = '+2thIt3EDRdZuOWyUKKzdSwwUPslVTXeEXoBjGazCag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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