SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5c0f937640ff81bf7b51188875f66af7dac5d8b426b447513f9dff9265cc986' 
  AND token = 'LGhBVwpoC06dDpShVawrSJNB2rpbF+lwGcUu1TLzTfU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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