SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '108503867bfbaabc892bbf587244f43ad83fb759a43f825c5e39320af76ea20f' 
  AND token = 'X/ddmjQRpGDFz66lFH8As6EkPp/a9shcwwjv9HbPJGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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