SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '691f99a03d5802e3cef0a7263bab60288592fd003f1dd29aaebf282409d5110d' 
  AND token = 'uWo/kHSYWgFFoeSkX6LIcip+oywVAh16DK3AkuNWJ6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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