SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1dca9544c39d29f31db9cf464978ce20628c7d52438deba4ac30514987b3853' 
  AND token = 'MIGay5bw1rDVh5AbtHPJQmRJvOi50/YnS4w8tWfuFtY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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