SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7119acae6fdfc21a9eef1750f05bee136536c991f99348307a527089566b543f' 
  AND token = '2vjb5wrEs4gmC/G0g+56WLzPHmoKlDEY8vN5rfLusF8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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