SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '371e630dbba8814aa76338241293416b187525881a5144297046a5a8fed9a2ad' 
  AND token = '8xA8CdGIvHAV0G2HlYkKKZh94FP7Y1YyYk6x9JCSj4c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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