SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '44b0003c7df5183f6789f9397f277686527e96a0947cef20537bffba47c96d71' 
  AND token = '8VEBqq3AV3+bH6CZ2GtzLjnuZRynL5BkMas19zmasFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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