SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'dc1b8bd93d06388b1774f961eaafedad4deeb979c3bcb896999ee45541eda83c' 
  AND token = 'ywBcfHjP3/Dp5LYv91cxQYH0yRGCZB1dFRx6jmJtS4o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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