SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '507c2541c29ea377a0f09c86d8caedf48fefcb22d7a39b17b2f7d6b5e2dca26e' 
  AND token = '81jSZTN61YTN7oGoAT8hxcM0ISzuAoC85fFIxB3i8Ag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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