SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '765c255f17a6c7207ddf434c2312f8658874f9a05551b30d9abe9e9a34c84a58' 
  AND token = '/vJvQwXylnrZ3Q8KmQzjikoRywyV3TnBZYkBfpWT0N0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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