SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18733f11d3265f1c18645d5dbcf65a207a145003d2ef00fefa7aee42ac3aa961' 
  AND token = 'i+XWISaKudjdnYMwiGRcZtGoGddIrQVdnzUrWZzUsAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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