SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '700929d42585ef110096ef95663a513ba8be8382e12e7395779039830ed4c684' 
  AND token = 'BnUPFlXjR4nMNIbRayfU8hgqFBx6d6jMRmAcxvicbSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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