SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77574463f232618aa0a973ce85e0153a8a4dbd6407e08902d4530feeb1ceb555' 
  AND token = 'T8pKAvRtU4OfZiMUkfjMd3cRTCY//oBoIkGtKG6EyD4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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