SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0c21553769dba90af7d293f96b646777857cfa16df27eac5a7ce52add81e3b6' 
  AND token = 'SyYdZwJy2+R8PjoGdjVUzYt3WK4c/vRXiLChdZKYeAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00060

JSON explain

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