SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '275f0760feb7e1a6f57acee51304e74ff28ffcc62dd1f50352672b1399d37344' 
  AND token = 'mQZkR8nzLxsxacy4AkY2xQdVuwXlxZY1ksecqrARjhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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