SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac1c588c8cb812425646262b00721ad86d8eedc54e87ac2bbef2214569fb99d4' 
  AND token = '83LiFKzjJICUBipsipNTBvQiB+8Ktr/DhJIk0rVthVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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