SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16bc34563d7c69fec36a5dda458d7ced62a438d7297a85fb447a84a667b59281' 
  AND token = '7Qmk/LFb81GKvUBVMcbPjbH3x/e2+CuL7/vvciTV1wI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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