SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7624fa54f4a19d17f89c377c065aba7b6863f134ced74b56dc692098a36855fa' 
  AND token = '+zC+ddNwSmYnCherSndnEaxnSG3edqQDhApjCNJMTL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00073

JSON explain

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