SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4b6484e688573ff974208c802390c8e111336d3e6ec9852237fb65d742d3b10' 
  AND token = 'UmohL9QOjfypTQwZYqvb+5NhKSp7r9G7YlHtrco+KbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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