SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e168f3682f37c0b724273703e0b162eb5307d8314f4621b1120ff2c4869fe7fa' 
  AND token = '/oN0VmbLHQPB9ZE3qI8AoTvamcctoh8I8p30IsRQKUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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