SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '2973aa31cbe81f270762737b16350e16478880ddadbdb833efda1b71522591af' 
  AND token = 'WdO2nNkZtw0LZ6+Y3+fArHYBW8Bhf5OSY6g1OXULJq8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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