SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcf6047b82d816959010f2aebe06b6478ebe385826ebfc8a41ab8354f44999d1' 
  AND token = 'N7dxIYhNe8ElPUu3Ck2RBrZnE0QoQyLCM5X5Axu8ye8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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