SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '429c4cbf762c79f254b96e90c22db47012fbd888500b7a21b7fcc5719d7a4aef' 
  AND token = 'GUdPrKmmwOpVwaxuEizGYJwKlV0GfWFq2Bk97v6n8yQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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