SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70df46443352981ccc772791600dcbe9f159404c7a309400b979fd1e03157b00' 
  AND token = 'zbLfLVwpq2+tSGOCH71Wy/wwcHMVLeA3+mTNjz9lIWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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