SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81b58f7697bf7b4f6d80ecb29389e75c3e14f5479ec752e594cc49a1e7f754fa' 
  AND token = 'buFsDoU+c/QqcqJYc11x7biCemILwZSWELcvy1wy6EU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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