SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b392c125af87dad8c54dfc63a404b422fa83ab1cf7f73f7739295b5904ffbd52' 
  AND token = 'Wpyggu7t8ygVzJ2hPCVOKmpSS1BrSixLfMsx8/bZY8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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