SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43d6421a6599dd35d3a645fe45619bed92ba15f5d62181cfa39b9ffd0141b6db' 
  AND token = 'OJgMXn5KksVNZv1WMR1PU+OZ4lGuRDt2iNVhMryAR8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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