SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2623dad0e77d25eb71a8929fc3d39c726b89f68f5c4b317af46e4dcf0a55401d' 
  AND token = 'XLUB4zHyH/zCTHCosy0D5Z//ip8qsGXPyMY8N4Tf97g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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